Ballast for fluorescent lamp



March 17, 1959 KEIZO KUDOH 2,373,425

' BALLAST Fon FLUORESCENT LAMP Filed Sept. 26, 1957 2 Sheets-$heet 1 Fig.4

Ka'zo Kudoh 1 N VE N TOR @4052... BY Wavy March 17, 1959 KEIZO KUDOH BALLAST FOR FLUORESCENT LAMP 2 Silesia-Sheet 2 Filed Sept. 26, 1957 Keizo Kudoh IN VEN TOR.

United States I Patent 2,878,425 BALLAST FOR FLUORESCENT LAMP Keizfi Kndoh, Ota-ku-Tokyo, Japan Application September 26, 1957, Serial No. 686,442 1 Claim. (Cl. 315-284) This invention relates to a ballast choke for use with a circular fluorescent lamp.

The primary object of the present invention resides in the provision of a ballast choke which is of a configuration as to correspond to the shape and size of a circular fluorescent lamp thereby enabling highly attractive lighting fixtures to be constructed.

A further object of the present invention resides in the provision of a ballast choke that is simple in construction, capable of being housed in a relatively small cylindrical housing for use in combination with a circular fluorescent lamp with the housing having means appended thereto for supporting and suspending the fluorescent lamp therefrom whereby a highly attractive lighting fixture can be obtained.

A further object of the present invention resides in an arrangement of a ballast choke for use with a circular fluorescent lamp which employs novel means for forming a magnetically closed circuit thereby producing an impedance.

These, together with the various ancillary objects and features of the invention which will become apparent as the following description proceeds, are attained by this ballast choke for a circular fluorescent lamp, a preferred embodiment of which has been illustrated in the accompanying drawings, by way of example only, wherein:

Figure l is-a perspective view of the invention showing in combination the fluorescent lamp suspended from the housing having the ballast choke mounted therein;

Figure 2 is a horizontal sectional detail view as taken along the plane of line 2-2 in Figure l and being shown on an enlarged scale for clarity;

Figure 3 is a perspective view of the ballast choke;

Figure 4 is an enlarged vertical sectional detail view as taken along the plane of line 4-4 in Figure 3;

Figure 5 is a perspective view of one of the plies of the ring disk utilized in the invention; and

Figure 6 is an exploded perspective view of the ballast choke.

With continuing reference to the accompanying drawings wherein like reference numerals designate similar parts throughout the various views, reference numeral 10 generally designates the lighting fixture comprising the present invention which includes a housing 12 having clips or other support elements as at 14 secured thereto in any convenient manner which clips or supports serve to support a circular fluorescent lamp 18 which is of substantially the same diameter as the housing 12 therebeneath. As indicated at 16 there is provided a plug-in connection to the housing 12 for connecting the circular fluorescent lamp 18 to the ballast choke comprising one of the important elements of the invention and to the source of electrical power for the circular fluorescent lamp 18. The ballast choke is adapted to fit within the housing 12 and is circular in shape and therefore aids in allowing the fixture 10 to be of attractive appearance by its relatively small size. It is to be understood that the circular fluorescent lamp 18 and the housing 12 may be quite small in size due to the particular construction of the ballast choke comprising an important sub-combination of the invention. This ballast choke is generally indicated by reference numeral 20 and the various parts thereof can be seen best in Figure 6. A ring coil 22 which is suitably wrapped with insulation as at 24 is provided and has leads 26 and 28 extending therefrom. This coil 22 is ring shaped and seats within an outer core 30 formed of a single strap of magnetic material such as suitable ferrous material or the like or may be formed in lieu of the single strap 30 of a plurality of concentric plies which plies are also formed by the strap arrangement. The inner core 34 consists of a plurality of concentric rings as at 36 of suitable magnetic material such as iron or iron alloys. Optionally, the inner core 34 may be formed as is the outer core 30 from a single strap of material forming a plurality of plies after being wound upon itself. A pair of recesses 38 and 40 are formed in the edge of the inner core. Upper and lower ring disks as indicated at 42 and 44 sandwich the inner and outer cores and the ring coil therebetween. Each of the ring disks comprises a plurality of plies and each of the plies is divided into sections as indicated at 46 and 48. Each of the sections is formed of a suitable magnetic material and has a recess as indicated at 50 and 52 therein through which bolts as indicated at 54 extend which bolts serve to tie and assemble the entire ballast choke together. The bolts 54 pass through the recesses 50 and 52 and between the outer core 30 and the ring coil 22. A single ply is seen in Figure 5.

In the assembly, the conductors 26 and 28 will seat in the recesses 38 and 40 and may optionally be passed directly through apertures, not shown, formed in the ring disks. Of course, a suitiable starter as at and support means as at 72 may be provided for the entire lighting fixture 10 and optionally a central indicator light may be provided as desired. This fluorescent lamp fixture 10 is especially adapted for use on sewing machines and the like.

The foregoing is considered as illustrative only of the principles of the invention. Further, since numerous modifications and changes will readily occur to those skilled in the art, it is not desired to limit the invention to the exact construction and operation shown and described, and accordingly all suitable modifications and equivalents may be resorted to, falling within the scope of the invention as claimed.

What is claimed as new is as follows:

A ballast for a circular fluorescent lamp in combination with a cylindrical housing having a circular fluorescent lamp suspended therefrom, said ballast being disposed in said housing and including a multiply inner core of magnetic material, a multiply outer core of magnetic material concentrically disposed about said inner core, a ring coil disposed between said inner core and said outer core, ring disks of magnetic material positioned above and below said inner core, said ring coil and said outer core, said inner core, said ring disks, and said outer core forming a, closed continuous magnetic path about said coil; References Cited in the file of patent andconductors connected to said ring coil, said ring dis,

each comprising a plurality of plies with each of said UNITED STATES PATENTS plies including a plurality of sections, and fasteners ex- 432,050 Kammeyer July 15, 1890 tending between said ring disks and between said outer 5 678,047 Shoemaker July 9, 1901 core and said ring coil holding said ballast assembled, 1, 03,868 Porter May 5, 1931 said inner core having recesse therein, said conductors 2,472,597 Levy June 7, 1949 extending between said inner core and one of said ring 2,498,702 Nahman Feb. 28, 1950 disks and seating in said recesses, said housing being 2,655,623 Parker Oct. 13, 1953 substantially the same outer diameter as said fluorescent 10 2,703,391 Gunderson Mar. 1, 1955 a 2,708,713 Lane May 17, 1955 lamp. 

